CN103952676B - A kind of BaTi of b axle orientation 2o 5the preparation method of film - Google Patents

Abstract

The invention discloses a kind of BaTi depositing b axle orientation on electrode materials ₂o ₅the technology of preparing of film.By BaTi ₂o ₅on the substrate that pottery adopts the mode of pulsed laser deposition or magnetron sputtering to be deposited on to be coated with Pt electrode, obtain amorphous BaTi ₂o ₅film; Then be placed in 900-1000 DEG C of stove by the substrate depositing film and anneal, be placed in DC electric field by sample during annealing, field intensity is 200-3000V/cm, anneals and within 1-2 hour, can obtain height b axle orientation BaTi ₂o ₅film.The present invention can prepare BaTi on Pt electrode ₂o ₅film, the film prepared has height b axle orientation; And present invention process is simple, with low cost, and can be applicable to prepare other oriented film, have broad application prospects.

Description

A kind of BaTi of b axle orientation 2o 5the preparation method of film

Technical field

The present invention relates to a kind of BaTi ₂o ₅the technology of preparing of ferroelectric membranc, particularly a kind of BaTi depositing b axle orientation on electrode materials ₂o ₅the technology of preparing of film.

Background technology

Ferroelectric membranc has good dielectric, piezoelectricity, ferroelectric, the characteristic such as pyroelectricity, photoelectricity and nonlinear optics, has a wide range of applications in fields such as microelectronics, photoelectron, integrated optics and microelectromechanical systemss.In recent years, ferroelectric membranc receives extensive concern as the commercial applications of Ferroelectric Random Access Memory.Ferroelectric Random Access Memory (be called for short FRAM) has non-volatile, high read or write speed, high storage density, reduce power consumption, low-work voltage and the repetitive read-write advantage such as often, in a lot of fields such as information processing, transmission and mobile communication, there is boundless application prospect.BaTi ₂o ₅it is a kind of novel lead-free ferroelectric material.It has, and specific inductivity is large, Curie temperature is high, is easy to existing traditional memory technology mutually compatible, is convenient to the feature of the commercial applications of product.Current BaTi ₂o ₅film, particularly has the BaTi of orientation ₂o ₅the technology of preparing of film also lacks very much, rarely seen employing pulsed laser deposition technique, is prepared the BaTi of certain b axle orientation by regulation and control mode of deposition ₂o ₅film.Mainly by first depositing and BaTi on substrate ₂o ₅the MgO that lattice is close, and then obtain b axle orientation BaTi by epitaxy ₂o ₅film (CN201010137524).And must be deposited on electrode materials (being generally Pt) as the ferroelectric membranc that ferroelectric memory uses.Adopt pulsed laser deposition technology, (substrate temperature 670 DEG C, oxygen pressure 12.5Pa) is at Pt (111)/Ti/SiO under severe conditions ₂/ Si deposition on substrate has gone out the BaTi with certain b axle orientation ₂o ₅film (J.Wangetal./JournalofAlloysandCompounds512 (2012) 140 – 143).Current technology is difficult to the BaTi preparing high orientation efficiently on Pt electrode ₂o ₅film.

Summary of the invention

The object of the invention is the BaTi providing a kind of height of deposition b axle orientation on electrode materials ₂o ₅the method of ferroelectric membranc.

For achieving the above object, adopt technical scheme as follows:

A kind of BaTi of b axle orientation ₂o ₅the preparation method of film, is included in the deposition on substrate being coated with Pt electrode materials and goes out amorphous BaTi ₂o ₅film, then puts into stove and anneals under electric field-assisted.

A kind of BaTi of b axle orientation ₂o ₅the preparation method of film, comprises the following steps:

By BaTi ₂o ₅on the substrate that pottery adopts the mode of pulsed laser deposition or magnetron sputtering to be deposited on to be coated with Pt electrode, obtain amorphous BaTi ₂o ₅film; Then be placed in 900-1000 DEG C of stove by the substrate depositing film and anneal, be placed in DC electric field by sample during annealing, field intensity is 200-3000V/cm, annealing 1-2 hour.

Present invention utilizes BaTi ₂o ₅only there is the feature of excellent ferroelectric properties on b direction of principal axis: only have 140 and 70 along other two axial specific inductivity, and the axial specific inductivity of b can reach 20000, easily occur polarization at b direction of principal axis.When direction of polarization (along b axle) is consistent with direction of an electric field, free energy is minimum, therefore by preferentially growing in this direction, realizes the oriented growth of b axle.First the present invention goes out amorphous film at deposition on substrate, then high temperature annealing, and when utilizing electric field to regulate and control to anneal, crystal growth process, realizes the preferred orientation of b axle.BaTi ₂o ₅during crystalline growth, its direction of growth is by substrate and BaTi ₂o ₅the impact of interfacial energy, strain energy.When not applying externally magnetic field effect, generally there will be with substrate lattice closer to oriented growth (when being coated with Pt, being generally (510) orientation).Only have when extra electric field reaches some strength, coherence can be overcome when affecting, just there will be the growth consistent with direction of an electric field.But electric field can not be too large, and time too large, in stove, atmosphere (N2) can puncture.

The present invention and existing BaTi ₂o ₅method for manufacturing thin film is compared has following advantage:

BaTi can be prepared on Pt electrode ₂o ₅film, the film prepared has height b axle orientation;

Technique is simple, with low cost, and can be applicable to prepare other oriented film, has broad application prospects.

Accompanying drawing explanation

Fig. 1: the non-crystalline state BaTi before embodiment 1 annealing ₂o ₅film.

Fig. 2: embodiment 1 anneal after film thing phase.

Fig. 3: the film thing phase that embodiment 2 obtains.

Fig. 4: the film thing phase that embodiment 3 obtains.

Fig. 5: the film thing phase that embodiment 4 obtains.

Fig. 6: the film thing phase that embodiment 5 obtains.

Fig. 7: the film thing phase that embodiment 6 obtains.

Fig. 8: the film thing phase that embodiment 7 obtains.

Fig. 9: the film thing phase that embodiment 8 obtains.

Figure 10: the film thing phase that embodiment 9 obtains.

Figure 11: the film thing phase that embodiment 10 obtains.

Embodiment

In order to understand the present invention better, below in conjunction with embodiment and accompanying drawing, the invention will be further described, but content of the present invention is not only confined to the following examples.

The BaTi of height b axle orientation ₂o ₅the preparation method of film: go out amorphous BaTi at the deposition on substrate being coated with Pt electrode materials ₂o ₅film, then puts into stove and anneals under electric field-assisted.Present method can prepare BaTi on Pt electrode ₂o ₅film, the film prepared has height b axle orientation.

The BaTi of height b axle orientation ₂o ₅the preparation method of film, step is as follows:

By BaTi ₂o ₅on the substrate that pottery adopts the mode of pulsed laser deposition or magnetron sputtering to be deposited on to be coated with Pt electrode, obtain amorphous BaTi ₂o ₅film; Then be placed in 900-1000 DEG C of stove by the substrate depositing film and anneal, be placed in DC electric field by sample during annealing, field intensity is 200-3000V/cm, anneals and within 1-2 hour, can obtain having height b axle orientation BaTi ₂o ₅film.

Present method make use of BaTi ₂o ₅only there is the feature of excellent ferroelectric properties on b direction of principal axis: only have 140 and 70 along other two axial specific inductivity, and the axial specific inductivity of b can reach 20000, easily occur polarization at b direction of principal axis.When direction of polarization (along b axle) is consistent with direction of an electric field, free energy is minimum, therefore by preferentially growing in this direction, realizes the oriented growth of b axle.First the present invention goes out amorphous film at deposition on substrate, then high temperature annealing, and when utilizing electric field to regulate and control to anneal, crystal growth process, realizes the preferred orientation of b axle.BaTi ₂o ₅during crystalline growth, its direction of growth is by substrate and BaTi ₂o ₅the impact of interfacial energy, strain energy.When not applying externally magnetic field effect, generally there will be with substrate lattice closer to oriented growth (when being coated with Pt, being generally (510) orientation).Only have when extra electric field reaches some strength, coherence can be overcome when affecting, just there will be the growth consistent with direction of an electric field.But electric field can not be too large, and time too large, in stove, atmosphere (N2) can puncture.Meanwhile, present method technique is simple, with low cost, and can be applicable to prepare other oriented film, has broad application prospects.

Embodiment 1

With BaTi ₂o ₅pottery is target, adopts laser pulse (PLD) depositing the MgO deposition on substrate BaTi of Pt electrode ₂o ₅film.Mode of deposition is O ₂dividing potential drop 12.5Pa, laser energy density 2J/cm ², substrate temperature 25 DEG C.Product is see accompanying drawing 1, BaTi ₂o ₅for non-crystalline state.Then BaTi will be deposited ₂o ₅the tube furnace that temperature is 850 DEG C put into by the substrate of film, anneals 2 hours, applies the DC electric field of 200V/cm voltage simultaneously.Thing after annealing is met each other Fig. 2.BaTi after annealing ₂o ₅resolve into BaTiO ₃.

Embodiment 2

Annealing temperature in embodiment 1 is become 900 DEG C, and the thing after annealing is see accompanying drawing 3.Originally amorphous film is no longer resolve into BaTiO ₃, but be transformed into the BaTi of crystallization ₂o ₅film, and in b axle orientation.

Embodiment 3

Annealing temperature in embodiment 1 is become 950 DEG C, and the thing after annealing is see accompanying drawing 4.Originally amorphous film is no longer resolve into BaTiO ₃, but be transformed into the BaTi of crystallization ₂o ₅film, in b axle orientation, crystallinity is better than 900 DEG C of annealed sample.

Embodiment 4

Annealing temperature in embodiment 1 is become 1000 DEG C, and annealing time is 1 hour.Thing after annealing is see accompanying drawing 5.Originally amorphous film is no longer resolve into BaTiO ₃, but be transformed into the BaTi of crystallization ₂o ₅film, in b axle orientation, crystallinity is better than 950 DEG C of annealed sample.

Embodiment 5

Annealing temperature in embodiment 1 is become 1050 DEG C, and annealing time is 1 hour.Thing after annealing is see accompanying drawing 6.Non-crystalline state BaTi after annealing ₂o ₅film resolve into BaTiO ₃.

Embodiment 6

DC electric field when embodiment 4 being annealed is removed, and the thing after annealing is see accompanying drawing 7.Mainly see the diffraction peak of MgO matrix.Be also shown in BaTi ₂o ₅(510) and (020) diffraction peak.Illustrate when without electric field, BaTi ₂o ₅oriented growth not obvious.

Embodiment 7

DC electric field in embodiment 4 is become 500V/cm, the thing after annealing see accompanying drawing 8, non-crystalline state BaTi ₂o ₅film be transformed to crystalline state, and b axle orientation is better.

Embodiment 8

DC electric field in embodiment 4 is become 2000V/cm, and the thing after annealing, see accompanying drawing 9, obtains the better BaTi of b axle orientation ratio voltage 1000V/cm ₂o ₅film.

Embodiment 9

DC electric field in embodiment 4 is become 3000V/cm, and the thing after annealing, see accompanying drawing 10, obtains the BaTi of b axle orientation ₂o ₅film is suitable when orientation and crystallinity and 2000V/cm field intensity.

Embodiment 10

With BaTi ₂o ₅pottery is target, adopts magnetron sputtering depositing the MgO deposition on substrate BaTi of Pt electrode ₂o ₅film.Product thing is met each other Fig. 1, in non-crystalline state.Then BaTi will be deposited ₂o ₅the tube furnace that temperature is 950 DEG C put into by the substrate of film, anneals 2 hours, applies the DC electric field of 2000V/cm voltage simultaneously.Thing after annealing, see accompanying drawing 11, obtains the BaTi of crystallization ₂o ₅film, in b axle orientation.

Claims (1)

1. the BaTi of a b axle orientation ₂o ₅the preparation method of film, is characterized in that comprising the following steps:

By BaTi ₂o ₅on the substrate that pottery adopts the mode of pulsed laser deposition or magnetron sputtering to be deposited on to be coated with Pt electrode, obtain amorphous BaTi ₂o ₅film; Then be placed in 900-1000 DEG C of stove by the substrate depositing film and anneal, be placed in DC electric field by sample during annealing, field intensity is 200-3000V/cm, annealing 1-2 hour.